Re: [PATCH 7/8] usb, cdc-acm: optimize barrier usage for Rmw atomic bitops

[Davidlohr Bueso]

ping? Can these please be picked up?

On Wed, 29 Jan 2020, Davidlohr Bueso wrote:

> We can avoid the unnecessary barrier on non LL/SC architectures,
> such as x86. Instead, use the smp_mb__after_atomic() call.
>
> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
> ---
> drivers/usb/class/cdc-acm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
> index 62f4fb9b362f..0bc4b558f387 100644
> --- a/drivers/usb/class/cdc-acm.c
> +++ b/drivers/usb/class/cdc-acm.c
> @@ -842,7 +842,7 @@ static void acm_tty_unthrottle(struct tty_struct *tty)
> 	clear_bit(ACM_THROTTLED, &acm->flags);
>
> 	/* Matches the smp_mb__after_atomic() in acm_read_bulk_callback(). */
> -	smp_mb();
> +	smp_mb__after_atomic();
>
> 	acm_submit_read_urbs(acm, GFP_KERNEL);
> }
> --
> 2.16.4